Wild cats have a different way of showing dominance than simply raising a tail. They tend to do more vicious things. Plus, unlike housecats, they have pre-established rankings with each pack/pride having an alpha male, so it is unnecessary to constantly show dominance by holding up their tails.
By Sarah Hartwell, http://www.messybeast.com: CAT COMMUNICATION - BODY LANGUAGE2002-2009, Sarah Hartwell "Feline body-language is complex and subtle with ate least twenty-five different visual signals used in sixteen combinations. There are doubtless many other, more subtle, nuances which we don't notice."
My theory... domestic cats generally aren't hormone driven, and live in a limited territory where they know all members in it are friendly, thus the "up tail" (which is a "happy to see you" position), where feral cats walk around with their tails in the neutral-to-potentially aggressive position.
Really? I was going based off my personal experience. When we brought my roommate's girlfriend's cat into the apartment for a few days, he got out of my roommate's room and Tails, who is the dominant one, crouched his front paws, stuck his butt in the air with his tail up and rigid, and started hissing and growling at the other cat. I figured that was the norm.
Rad, it sounds to me like what you're describing is the "bristling" tail, even though maybe it wasn't puffed up? But the O.P. was asking about the position of the tail while just walking around, not when encountering other cats or another cat for the first time.
"Just walking around" tails are up, hooked, angled, or under. Our Billy, outside, walked around with his tail tucked under - he was a VERY submissive kitty. But whenever he'd see his brother - "SPROING" - his tail would pop straight up, they'd run at each other, rub against each other, and wrap their tails around each other, and walk together with their tails entwined.
While kitty can have a "bristling" tail, it's not a normal "walking around" kind of tail. ...and it doesn't denote "dominance" so much as it denotes anger/upset.